What is the difference between flying birds and birds? A clear explanation of the differences between the two

Bird is the general term for all poultry, and flying bird is only one kind of poultry, different from poultry that cannot fly. Bird and flying bird differ only in the scope of the concept.

What is a bird? A bird is the general term for flying birds. Birds originally evolved gradually from reptiles into higher vertebrates, and are the only animals covered in feathers, so they are also called “feather animals”. Feathers help birds spread their wings and fly, and also help keep the bird's body warm.

Flying birds, flying birds. In the Warring States period, Song Yu of Chu wrote in “Rhapsody on Mount Gaotang”: “Their form resembles running beasts, or resembles flying birds.” In the Northern Wei dynasty, Li Daoyuan wrote in “Commentary on the Water Classic? Rivers, Part Two”: “Flying birds that flap their wings in the clouds, none do not fall into the deep waves.” Xu Chi wrote in “Record of Mount Huang”: “Besides all kinds of running beasts, there are also all kinds of flying birds.”

In the animal world, besides birds, insects and bats, which are truly flying animals, there are also groups of flying fish, flying squid, flying frogs, flying lizards, flying snakes, flying squirrels, flying mice and so on. Amphibians, reptiles and mammals can also “fly”, that is, glide, but none of them have feathers, so they are not birds. But the flightless kiwi, ostrich, emu, cassowary, penguin and others are birds because they have feathers. Likewise, turtles, ants and others that lay eggs and have no feathers are not birds either. Especially the peculiar platypus, which has a rubber-like duck bill and is the only surviving member of the mammal family that reproduces by laying eggs. In taxonomy, they belong to the monotremes. Although monotremes reproduce in the same way as birds, urinating, defecating and laying eggs all through the same excretory tract, because they have no feathers, they do not belong to birds either.